(1) Field of the Invention
The present invention relates to a drive and steering mechanism for a human powered vehicle. In particular, the invention is well suited for human powered vehicles that allow a rider to drive forward by transferring power from upper and lower body muscle groups using a smooth natural motion similar to running.
(2) Description of the Prior Art
Human powered vehicles, such as bicycles or boats and other water vehicles, are known in the art and are generally comprised of a frame for supporting the rider, a drive means for providing thrust, a steering means, and a power linkage with which the rider can transfer muscle-generated power to the drive means. The power may be generated by movement of the arm, the legs or both arms and legs.
Bicycles, for example, are normally constructed of a frame, a drive means comprised of a leg powered, pedal-driven rotatable sprocket that is connected by a continuous chain to a second sprocket communicating with the rear bicycle wheel, and handlebars that are attached to a fork supporting a steerable front wheel. It is also known to supplement the power of the rider""s legs by providing a linkage from the handlebars to the drive means or to the front wheel of the bicycle, so that movement of the handlebars by the rider""s arms creates an additional propelling force. The following list of U. S. patents disclose various drive mechanisms for converting handlebar motion, other than steering motion into forward motion of a bicycle or tricycle.
Of particular interest is U.S. Pat. No. 377,610 to Goodsell, which discloses an oscillating drive mechanism for a velocipede. A rod linkage transmits forces from the velocipede""s handlebars to a ratchet coaxially fixed to a foot pedal crank. The disclosed ratchet drive only transfers power on a down stroke of one side of the handlebars. A down stroke of the other side of the handlebars is a resting stroke.
Another patent to Goodsell, U.S. Pat. No. 384,150 replaces the ratchet drive with a friction clutch. However, the friction clutch does not increase the efficiency of power transfer because like Goodsell""s previous ratchet design, only a down stroke of one side of the handlebars transfers power. Furthermore, both patents disclose mechanisms that are asynchronous relative to the motion between the handlebars and foot pedals.
Yet another patent of interest is U.S. Pat. No. 2,510,013 to Edgar that discloses a bicycle having a linkage connecting a crank and pedal to a complex steering apparatus having a pair of handlebar levers that function as steering inputs as well as rockers for converting a bobbing motion of a rider""s upper body into rotary motion driving the rear wheel of a bicycle. The bobbing motion of the rider""s upper body forces both handlebar levers up and down in unison. The pedal movements are synchronized to the movements of the handlebar levers by the linkage connecting the crank and pedal to the steering apparatus.
The following patents are representative of prior art human powered drive mechanisms used to propel boats:
However, in spite of the numerous human powered drive mechanisms described in the prior art, there is still a need of a drive mechanism that enables the rider to apply continuous leg and arm forces to a drive means through the entire thrust cycle, with the foot and arm movements being synchronized so that the two movements supplement each other instead of counteracting each other. There is a further need for a drive mechanism that that will not interfere with steering of the vehicle during use. In addition, there is a need for a drive mechanism that includes an arm powered section that can be readily disengaged when the supplemental power is not desired, and later reengaged.
The present invention addresses these needs by providing a unique drive and steering mechanism for human powered vehicles, such as a bicycle or a human powered boat. The mechanism enables the operator to efficiently apply both arm and leg power for motive force while maintaining the ability to steer using the arms. The mechanism couples the arm and leg motion in a harmonious union similar to a running motion but can be easily uncoupled should the operator prefer to power the vehicle only with leg power. The mechanism enables motive power to be applied with both the up and down stroke of both arms. The mechanism is mechanically simple and is well suited to be applied to new vehicle designs as well as added on in kit form to existing vehicles, such as standard bicycles. The mechanism maintains the time tested spatial relationship between the seat, handlebars, and drive pedals of a standard bicycle, as well as the time tested and simple rotatable handlebar steering of a standard bicycle.
It should be noted that this invention allows arm forces to be applied to the handlebars without unintentionally applying substantial turning forces to the handlebars, then, through the use of a unique linkage mechanism that maintains the above-mentioned spatial relationship, couples these forces with those applied by leg power to the foot pedals. It should also be noted that although the invention is shown applied to a standard bicycle, the mechanism could be used to power and steer human powered vehicles having a recumbent position. Existing technology such as chain, gears and universal joints can be relatively easily arranged to accommodate the different relative locations of steering elements, such as front wheels and rudders, and drive elements, such as rear wheels and propellers. In general, the invention can be used with any type of human powered vehicle having a drive that includes a rotatable front sprocket or shaft used to transmit torque to wheel(s) or propeller(s) or in anyone of several established manners, such as gears, belts or chains.
In general, the drive mechanism of the invention is comprised of foot-powered section; an arm-powered section, which is also used for steering; a linkage joining the arm and foot sections; and a thrust component operatively connected to the foot-powered section. The specific construction of each of the drive mechanism elements will depend upon the type of vehicle being driven and its design. For example, the thrust component of a bicycle may be comprised of a chain-driven rear wheel operatively connected to the foot-powered section by a chain drive, while the thrust section of a boat may be comprised of a propeller connected to the foot-powered section by a rotatable shaft. Also for steering input, the arm-powered section may be connected to the front wheel of a bicycle, or to the rudder of a boat.
The foot-powercd section is broadly comprised of a generally horizontal, rotatable axle that is operatively connectable to the thrust component, with left and right foot-powered pedals being connected to the axle, e.g., at opposite ends of the axle, by oppositely extending crank handles. The pedals are 180xc2x0 out of phase and travel in circular paths so that the right pedal is at its lowermost position when the left pedal is in its uppermost position, and vice versa. A sprocket or a gear can be attached around the axle to connect the axle to the thrust component.
The arm-powered section is broadly comprised of handlebars having integral left and right outer sections. The handlebars are pivotally connectable to a steering post so that the bars can oscillate on the post with each outer section being moveable between raised and lowered positions. Since the sections are integral, the right bar section will be in its lowermost position when the left bar section is in its uppermost position, and vice versa.
The foot-powered and arm-powered sections are connected so that the left pedal will be in its lowermost position when the right handlebar section is in its lowermost position and the right pedal will be in its lowermost position when the left handlebar section is in its lowermost position. As a result of this relationship, the relationship of the handlebar sections to each other, and the relationship of the pedal sections to each other, the rider is able to exercise a running motion when rotating the pedals and simultaneously oscillating the handlebars, thus creating a continuous cooperative relationship between the arm-powered and foot-powered sections permitting pushing down on the pedal of one side while pulling up with opposing force on the handlebar of that same side.
The exact configuration of the linkage joining the foot-powered section to the arm-powered section will vary somewhat depending on the type of vehicle and its overall construction. Generally, howvever, the linkage will be comprised of a pivotal first section having a first end attached by a flexible link to a handlebar section and an opposed second end, and a second section having a first end pivotally attached to the second end of the first section and a second end attached to a crank of the foot-powered section. The first section is comprised of telescoping inner and outer components, with the inner component being rotatable within the outer component, so that the handlebars can be turned to steer the vehicle.
In operation, the rider pushes downward on one of the pedals, e.g., the left pedal, while sinultanieously pulling up on the same side handlebar section and pushing downward on the opposite handlebar section, i.e., the right handlebar section. As the right handlebar section is moved downward, the first end of the first linkage section is pulled upward, pivoting the second end of the first section downward, thereby pushing the second linkage section downward against the left pedal crank to supplement the foot force being applied by the rider. When the left pedal and the right handlebar section simultaneously reach their bottommost positions, the rider pressed downward on the right pedal and the left handlebar section to continue application of force to, and rotation of, the axle to which the pedals are attached.
If desired, the linkage can be disconnected when use of the arm-powered section for driving purposes is not desired. When disconnected from the foot-powered section, the arm-powered section is used only for steering purposes and does not oscillate when the pedals are rotated. In this alternative, the second linkage section is comprised of first and second telescoping sections, with a first releasable latching means to secure the sections together and prevent telescoping or disconnected to permit telescoping when the handlebars are latched in position. A second releasable latching means is used to prevent oscillation of the handlebars on the steering post.
Each latching means is movable between engaged and disengaged positions, with one latching means being in the engaged position when the other latching means is in the disengaged position. A control means, such as a lever, which may be the first portion of the rear brake lever preceding brake application, connected to both latching means, to simultaneously move one latching means to the engaged position while moving the other latching means to the disengaged position. Thus, when disconnection of the linkage is desired, the lever is moved to disconnect the first latching means, permitting free movement of the two sections comprising the second linkage section, while latching the handlebars to the steering post to prevent oscillation. These latch positions can then be reversed to reengage the linkage connection.
While it is to be understood that the present drive mechanism is generally useful with various types of human powered vehicles, it will be described in the context of a bicycle for purposes of illustration. Generally, a bicycle is constructed of a frame of elongated tubes, including a head tube, a top tube, a down tube, a seat tube and a rear fork. The top end of the head tube is usually connected substantially perpendicular to a top tube and the bottom end of the head tube is connected to the down tube such that it slopes downwardly away from the top tube. A seat tube substantially perpendicular to the top tube collects the down tube to the top tube.
The foot-powered drive mechanism includes a front sprocket connected to an axle having a left side crank with a left side pedal and a right side crank with a right side pedal. Both pedals are rotatable along circular pathways between the top and bottom positions. The left side pedal is in the bottom position when the right side pedal is in the top position. The axle is rotatably attached to the bicycle frame through a bearing bracket joining the bottom ends of the down tube and the seat tube.
A rear sprocket is centrally attached to a rear wheel mounted to the rear fork of the bicycle frame. Normally, an endless chain connects the front sprocket to the rear sprocket. However, other drives, such as a drive shaft, can be used.
A fork mounted at the front of the bicycle frame includes a steering post at its top end that extends through and above the head tube. The bottom section of the front fork extends from the bottom end of the head tube in an arc away from and to the front of the head tube. A front wheel is rotatably mounted on the front fork""s bottom end handlebars are securely attached to the top of the steering post to rotate the post and thereby turn the front wheel to steer the bicycle.
Unlike a standard bicycle, the handlebars in the present invention are also oscillatable, and are linked to the foot-powered section to provide supplementary drive power to the sprocket. Specifically, the handlebars of the bicycle incorporating the present drive mechanism have integral left and right arm sections that extend to opposite sides of a central pivot point. The handlebars are pivotally attached through the central pivot point to the steering post near its top end. The left and right arm sections of the oscillatable, handlebars each have a top position and a bottom position. The left arm section is in the top position when the right arm section is in the bottom position. The left and right side pedals also have top and bottom positions.
A yoke secures the handlebars so that they remain transverse to the front wheel""s plane of rotation for all steering angles. The yoke also substantially limits the handlebars to a plane of oscillation that substantially contains the centerline of the steering post, so that force in this plane applies little or no steering torque to the steering output. In some configurations, as with a bicycle with a xe2x80x9crakexe2x80x9d angle, it may be advantageous to move this plane slightly in a direction toward a point where the tire of the front wheel contacts to ground.
The linkage basically comprises a generally horizontal telescoping first member section having a front end and a rear end and a generally vertical pinned telescoping second member section having a top end and a bottom end. The first member section is pivotally attached roughly midway between its first and second end to a bicycle""s top tube intermediate the head tube and the seat tube. The front end of the first member is pivotally attached to one of the handle bar sections and the second end of the first member is pivotally attached to the top end of the second member and the bottom end of the second member is attached to the drive.
The linkage connects the handlebars to the drive, whereby one full oscillation of the handlebars in cooperation with forces applied to the pedals rotates the sprocket one full revolution. Whenever a rider moves the handlebar left arm section to the top position the left pedal will be in the bottom position. A full oscillation of the handlebars occurs when either handlebar arm section travels once from its top position to its bottom position and back to its top position. One full oscillation of the handlebars also occurs when the front sprocket rotates through a 360xc2x0 cycle. Moreover, the linkage connecting the handlebars to the drive and pedals force the left arm section of the handlebar into the top position whenever the left pedal is in the bottom position.
The linkage attaches to one of the handlebars arm members at a point substantially distant from the handlebars central pivot point creating a lever arm for transferring power to the chain drive. The length of the lever arm, i.e. the distance from the handlebars pivot point to the attachment point of the linkage is predetermined to maximize handlebar power transfer while at the same time provide adequate steering.
In an embodiment of the present invention the linkages are constructed from metal rods and a tubular sleeve. One linkage rod referred to in this disclosure as a first telescoping rod is pivotally attached to a handlebar arm section by a universal joint allowing the attached end of the first telescoping rod to pivot left and right as the bicycle is steered, as well as up and down as the handlebars are oscillated. The connection between the handlebars and the first telescoping rod need not be limited in mechanical degrees of freedom. For example, the universal joint used in an embodiment of the invention is made of metal but the connecting of the linkage could be accomplished just as well by using a flexible material such as rubber. The first telescoping rod is also free to rotate within the drive sleeve.
In the preferred embodiment, the first telescoping rod is connected to the left arm section of the handlebars. The first telescoping rod slides and rotates within a tubular sleeve allowing for large steering angles. The sleeve referred to as the first drive sleeve is pivotally attached to the top tube of the bicycle frame or the pivot may be otherwise supported, such as by a compression bar to the down tube and simply stabilized by the top tube which would allow the present invention to be attached to and function properly with a recumbent bicycle or human powered boat, etc. The pivotal attachment of the first drive sleeve allows the rear end of the sleeve to arc upward or downward as the front end of the first telescoping rod arcs upward or downward, forced by the universal joint to follow the upward or downward movement of the handlebar left arm section. This pivot allows for roughly 20xc2x0 of pivoting in the vertical plane but also must allow a lesser degree of pivoting in the horizontal plane.
Pivotally connected to the rear end of the first drive sleeve is a second drive sleeve. The second drive sleeve receives a pinnable second telescoping drive rod with a rigidly attached drive bar, both extending downward to the left side crank. The drive bar has a bearing attached to its bottom end. The bearing is rotatably connected to a shaft rigidly coupling a crank pedal segment to an axle crank segment both belonging to the left side crank.
To instantly convert the functioning dual powered drive to a foot-powered only drive, a pair of latcles, such as simple pins or cogs or the like, can be activated by a mode lever convenient to one hand such that the second telescoping drive rod will be unpinned and allowed to telescope, thus freewheeling the leg drive from the arm drive. Instantly thereafter, the handlebars attached to the yoke will be pinned or locked to a steering post clamp. In this configuration the bicycle or other type of human powered vehicle will steer and pedal in the normal fashion. The mode lever has two positions, an engaged position and a disengaged position. The engaged position is for releasing the handlebars to pivot while locking the second telescoping drive rod. The disengaged position is for locking the pivotal handlebars while releasing the second telescoping drive rod.
When in operation with the mode lever in the engaged position, two continuous cooperating forces combine in rotating the front sprocket. One force is transferred from the handlebars to the front sprocket by the drive mechanism linkage and the other force applied to the front sprocket comes directly from the pedals. As a rider forces the left side handlebar section downward the front end of the first telescoping rod is forced to arc downward. The rear end of the first telescoping rod being inside the drive sleeve forces the rear end of the drive sleeve to travel in an upward arc pulling the pinned second telescoping drive rod and drive bar upward. The front sprocket rotates as the end of the drive bar pulls the left side crank. At the same instant the right side crank and pedal are forced downward by the right foot of the bicycle rider generating a cooperating force adding to the rotation of the front sprocket.
Conversely, as the rider forces the right side handlebar section downward the front end of the first telescoping, rod is forced to arc upward forcing the rear end of the first drive sleeve to travel downward, thus pushing the second drive sleeve and pinned second drive rod with drive bar downward. The front sprocket rotates as the end of the drive bar pushes the left side crank.
Thus, it is an aspect of the invention to provide a drive mechanism for a human powered vehicle that gives a rider an upper as well as a lower body exercise xe2x80x9cworkoutxe2x80x9d. The linkage for the drive mechanism has been designed such that the rider moves his or her body in a natural way that does not require any extensive practice to use the invention.
However. if the rider chooses he or she can to drive the bicycle in the normal fashion of pedal propulsion only with the pivotable handlebars locked in a standard steering position, the rider only needs to disengage the drive mechanism by moving the mode lever to the disengaged position. If on the other hand, the rider desires maximum speed or is on an uphill run where the dual drive aspect of the invention is so advantageous, the mode lever can be moved back to the engaged position releasing the pivotable handlebars and instantly thereafter pin or lock the telescoping drive rod to couple the motion of the pivotable handlebars to the sprocket.